Fire fighters need to find the location of a fire or fires as quickly as possible after they arrive at a building. Many fire departments assume that if a fire has not been actively fought within 20 minutes of its inception, the building cannot be saved.
Significant amounts of time can be spent trying to find the location of the fire, even when it is evident that there is a fire. Fire fighters arriving at a scene can often have a difficult time determining whether there is a fire. Even if it is determined that there is a fire, they often have difficulty determining where the fire is located.
Activation of one smoke alarm is an indication that there probably is a fire. Activation of multiple smoke alarms is a much higher probability indication that there is a fire. Activation of a sprinkler system, with resulting water flow usually is a nearly certain indication that there is a fire.
Occasionally a fire department is fortunate enough to pull up at the building and see visible signs such as smoke, or flames. In such cases, they can be certain from the onset that there is a fire and can proceed to searching for victims and the fire location. But these signs may not give any indication of where the fire is located in the building.
Smoke can travel through a building. Active smoke alarms are an indication of where smoke is, but the smoke may have traveled some distance from the fire.
Sprinklers are rarely activated unless they are subjected to the heat of a fire. An operating sprinkler is a very highly reliable indicator of the location of a fire. An operating sprinkler is a certain indicator of ongoing and substantial water damage. Establishing the location of operating sprinklers as quickly as possible is a high priority during an emergency. Increasing the speed with which an operating sprinkler can be located increases fire safety in buildings, and reduces the average overall level of damage by an incident.
Sprinklers make characteristic sounds when they are operating and water is flowing therefrom. Water makes sounds as it travels through the body of the sprinkler, strikes and deflects from the deflector, and as it strikes the ceiling and walls of the space that the sprinkler is mounted in. It is possible that under at least some circumstances, the sound of the water striking walls, the ceiling, and the floor of a space may be the loudest sound created by an active sprinkler.
Flow detectors can be used to determine that sprinklers are activated. Current sprinkler flow detectors do not give information about where individual sprinkler heads are flowing as a large number of sprinkler heads are usually associated with each flow detector.
Flow detectors are usually located, one per floor, at the main feed into the floor. At times they are installed less frequently. They are often not used due to facility management cost savings goals, limited code requirements and also due to operational issues associated with maintenance.
Flow detectors are generally difficult to maintain because they gunk up and corrode over time. Even a building that does frequent flow tests on its sprinkler system may find that there is a limited life for the flow detectors.
There is thus a continuing need for improved sensing systems which use, in some way, activated sprinkler heads as indicators of fire location. Preferably such results will be achievable without having to redesign the sprinkler heads. Additionally, it would be preferable if such flow sensing capability could be retrofitted in existing sprinkler systems.